How many seater you would like to go for. Based on no of seats I can guide you for the solution. If you are looking for more than 30 seater then I would suggest go for Ensemblepro dialer, I am implementing this product for the last 5 yrs. If you will compare with the cheaper solution:
1- Good answering machine detection
2- Lot of feature
3- redundancy and many more feature.
If you really interested for same plz do let me know I can guide you.